ER4SR in my ears for the past couple of days. I've got lots of listening in. Off the cuff thoughts: It's quite nice.. my first Ety, so I can't offer comparisons to previous versions. I actually like the deep fit. No need to fudge around finding tips, angles, and dealing with less than ideal isolation. They need to sell a small bottle of mineral oil with the damn thing cause you coat that on the silicon tips and they go in like butter. Sound is DF neutral.. linear to my ears. The general tuning leans to the dry side vs the more lush sounding Andro. ER4SR has excellent coherence... single BA drivers, duh. Soundstage is ok.. depth is lacking, width is quite good.. height is average. Imaging is fantastic here though and that takes priority over a large stage (for me). Microdynamics are terrific.. subtle detail is resolved effortlessly and presented with ample clarity. The Andro resolves micro detail more vividly and with more depth. Layering is better than expected.. not Andro good.. but better than some quad driver customs I've heard. Macrodynamics are quite passable.. again, not Andromeda good (duh). I need to get a DAC to more accurately get a sense of many of these technicalities, though. Tonally, this feels very accurate. Not quite as textured as some of the better multi-BA customs I've heard, but the ER4SR lack "sins of commission" when it comes to timbre. Note weight is a little leaner than i'd like.. but again, I need to her this off something better than my phone or chincy phone/amp combo. Lack of bass is a bit overblown, imo. Not really any slam, of course.. but the ER4SR has more punch than I was expecting and if you're used to a reference tuning, it's definitely presented in a way where it doesn't feel totally lacking or unrealistic. Bass is tight, fast, well textured, and extended. Decay is a hair faster than I'd prefer.. but I'll trade that for speed since I listen to a lot of liquid drum and bass, hip hop, and electronic music (and prefer a flat/reference-type tuning with these genres). Mids and treble are awesome. Again, very linear sounding.. it doesn't feel overtly forward or recessed anywhere here except the upper mids.. where there's a very slight sense of forwardness.. nothing offensive or jarring when listening at normal levels for extended periods of time.. even with less than well-recorded material (and as long as the fit is right). I really enjoying listening to these at low volumes. One thing that jumps out to me is how delicate and natural the midbass, midrange, and treble sound. There's an impressive sense of finesse and precision.. Ety knows what they're doing here. The ER4SR kind of reminds me of a slightly brighter LFF Paradox (the original, not Slants). More thoughts when I get a dedicated DAC. I bet the ER4SR would sound sweet off a good tube amp, btw. Thinking I might go back to customs though.. just miss the ease of fit.